The invention relates to a circuit arrangement for a mobile communications unit of a motor vehicle. The circuit arrangement has two mobile communications modules, wherein a mobile communications transmission is enabled on each of the mobile communications modules according to a predetermined mobile communications standard. The circuit arrangement further includes a reading unit for reading identification data from a chip card. In the context of the invention, a chip card refers to a UICC (Universal Integrated Circuit Card—universal card with an integrated circuit). Another term for such UICC is “SIM card” (SIM—Subscriber Identification Module). The present invention also relates to a method of operating a mobile communications unit having the described circuit arrangement as well as a UICC, i.e, a chip card, in which a Subscriber Identification Module (SIM) is integrated.
A mobile communications unit (Mobile Equipment) of a type that is integrated for example in a smartphone typically includes a mobile communications module for setting up a mobile communications connection in a mobile communications network via a wireless interface. In the context of the invention, a mobile communications module is the particular circuit unit which converts between digital payload data to be transmitted over the wireless connection and an analog mobile radio signal that can then be emitted via antennas. Mobile communications modules are commercially available under the designation GSM module (GSM—Global System for Mobile Communications), UMTS module (UMTS—Universal Mobile Telecommunications System) and LTE module (LTE—Long Term Evolution).
To enable a mobile communications unit to receive incoming calls or to set up calls, the mobile communications unit must be registered with a mobile radio network. This requires a SIM in the mobile communications unit. The SIM is a small processor with a memory, by which the mobile communications unit is assigned to a network and authenticated. For this purpose, secret numbers and algorithms are stored on the SIM. In connection with the mobile communications networks, UMTS and LTE, the SIM is also referred to as USIM.
Simultaneous transmission of voice and data is currently possible only with the UMTS mobile communications standard. The method defined in the GSM standard for the simultaneous transmission of voice and data is only scarcely supported by current GSM networks. LTE mobile communications networks currently do not support voice transmission and instead resort to an older standard UMTS or GSM for transmitting voice. Currently, only the GSM standard is supported in many regions. If only a single wireless module is used, the data transmission is interrupted when voice is transmitted.
The mobile communications unit may include two mobile communications modules to set up a data connection with the first mobile communications module and a voice connection with the second mobile communications module in a situation where the existing mobile communications standard does not allow a simultaneous transmission of voice and data. According to the current state of the art, two SIM cards are required for the simultaneous operation of the two mobile communications modules.
It can be expected in connection with the introduction of the mobile communications standard LTE that new problems with mobile coverage will arise when the new mobile communications standard is introduced. This may lead to coverage gaps which do not depend on the area, but on the services. The LTE mobile communications networks currently do not support the standard VoLTE proposed by LTE for voice transmission. It is therefore not predictable, how robust telephone connections will be. As taught by experience, the implementation of LTE and similar, novel communications standards in a vehicle will therefore likely encounter technical difficulties, so that it is desirable to have a redundant solution or a fallback position.